1. Technical Field
The present invention relates to a positioning system, a terminal apparatus, a method of controlling the terminal apparatus, a program for controlling the terminal apparatus and a computer-readable storing medium for storing the program for controlling the terminal apparatus, the positioning system and the terminal apparatus using a signal from a communication base station and a signal from a positioning satellite.
2. Related Art
Up to now, a positioning system using a GPS (global positioning system), which is a satellite navigation system, for example, for positioning a current position of a GPS receiver and a positioning system using a radio wave from a communication base station of a cellular phone have been put to practical use.
In a GPS receiver or a cellular phone, radio waves are received from three or more GPS satellites and/or communication base stations in total to calculate a distance between the respective GPS satellites or such and the GPS receiver or such (referred to as a pseudo range, hereinafter) on the basis of a difference between a time the radio wave is sent from each of the GPS satellites or such and a time the radio wave arrives at the GPS receiver or such (referred to as a delay time, hereinafter), for example. Positions of the respective GPS satellites or such and the above-mentioned pseudo range are used for performing a positioning operation of the current position. The positioning operation enables a positioning location composed of a longitude, a latitude and an altitude, for example, to be obtained.
The signals, however, are not always received from three or more GPS satellites and/or communication base stations.
On the other hand, proposed has been a technique for selecting a point nearest to a reckoned position of a mobile station out of points on a circumference, the points being intersections of two spherical surfaces whose radiuses are the pseudo ranges from the two communication base stations, which are the center of the spherical surfaces (in JP-A-2002-44711, for example).
JP-A-2002-44711 (FIG. 3 and the like) is an example of related art.
The above technique, however, has a problem that positioning is impossible when signals cannot be received from two communication base stations.